First you would want to distribute the 3 into the parentheses then you’ll get this:
3x-6+5x=18
Then combine like terms
8x-6=18
Then move the constant to the other side along with changing the sign
8x=18+6
Then add the numbers together
8x=24
Then divide both sides by 8
x=3
Then you are left with your answer,
x=3
Hope this helps! :3